Modem switched intelligent telecommunication networks typically comprise one or more central office switching systems trunked together, and connected to lines that which are directed to the various network subscribers. A variety of communication services are provided to the network subscribers via one or more service network elements connected to the switching systems. These services range from standard voice-band audio connections (also referred to as "narrowband" connections) established between two or more network subscribers, to broadband connections which allow subscribers to simultaneously exchange of audio, video, and/or digital data (such connections may be classified as "broadband/multimedia").
Within a switched telecommunication network, the network elements send predetermined commands to the switching systems relating to the particular service or services requested by a network subscriber. The switching systems configure themselves in response to the commands to effect the requested services. Despite wide acceptance of intelligent network architectures in principle, there has been no clear industry consensus on how to implement and deploy such systems. The most significant issues involved are the creation and control of complex call and connection configurations in the switching systems by the services network elements, along with resolution of interaction between commanded services and existing switching system features.
Existing methods of handling the complex control of intelligent switching systems (such as the method put forth in the Bellcore's "Advanced Intelligent Networks Technical Advisory," TA-NWT-001112, Issue 1, May 1991)require network elements, such as adjuncts and service control points ("SCPs"), to produce a set of low level service instructions to the switching system which directly manipulate call topology component resources in order to reach a desired switch configuration. These instructions directly manipulate low-level switching system resources and, therefore, contend for the use of these resources with existing switching system features. Typically, these low-level instruction sets do not follow any set pattern, and therefore result in difficult to solve feature interaction problems that directly impact all existing switch features. The required low-level transformations also are difficult to design and do not always naturally lead to a target switch configuration.
The drawbacks of this type of low-level, direct manipulation of an intelligent switching system are solved with respect to narrowband connections by the method and apparatus disclosed in co-pending U.S. patent application Ser. No. 07/880,727, filed on May 8, 1992 ("the '727 application"). Call processing within an intelligent switching system, per the '727 application, is effectively realized from a relatively small number of target call topologies, with the switching system producing transformations from one call topology to another. Such call topologies are implemented in the switching system as a set of call processing objects referred to as call configurations. The call configurations are entered into by the switching system in accordance with the commands of an object-oriented network services element that causes transformations from one call configuration to another by means of a relatively simple set of transfer commands (at least some of which represent a plurality of the low level commands similar to those proposed in the Bellcore Advisory).
Unfortunately, neither of these prior methodologies addresses the difficulties of establishing broadband/multimedia connections within a switched intelligent network. To effect a broadband/multimedia connection, two separate configurations (a call configuration, and a connection configuration) are required. This is due to the fact that not all of the network subscribers participating in the call will require (or be capable of accommodating) the same type of connection to the network. For example, of the participants in an audio/video conference call, some might only require a bidirectional audio connection, others might need a bidirectional audio connection and an omnidirectional video connection, still others might require that bidirectional audio and video connections be established. Clearly, attempting to effect such a complex interconnection via the low-level instruction set of the Bellcore Advisory would require a large number of commands to be sent by network adjuncts and SCPs. Although the target call topologies disclosed in the '727 application offer an improvement over the low-level Bellcore instruction set, they are adapted for the establishment of narrowband connections. Consequently, these target call topologies are incapable of effecting and accommodating the various call and connection configurations required within a broadband/multimedia telecommunication network.